At the last OPEC summit, Saudi Arabia pulled out of a deal at the 11th hour

One day left before the meeting in Vienna to close the Organization of the Petroleum Exporting Countries (OPEC) deal to reduce oil output, and the venture has devolved from being a sure thing to something needing to be rescued, according to a one-time deal booster.

Helima Croft, head of global commodities strategy at RBC Capital Markets, told CNBC from Vienna as pre-summit talks reportedly hit a wall, "We're going to need somebody to go in and rescue it; this could end early tomorrow unless Khalid" - Khalid al-Falih, oil minister for Saudi Arabia - "can come in and restore order, but there's not a lot of time to get it done."

Croft, who previously expressed optimism about the deal going through from media headquarters in the U.S., added, "What I hear is kind of crazy: the fear in town is it's Doha redux, everybody's worst nightmare."

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We're in the realm of ego…this is kind of lunacy

Helima Croft, RBC Capital Markets

She is referring the previous OPEC summit in Qatar, which had been widely dismissed by analysts as doomed to failure and indeed imploded when Saudi Arabia pulled out at the 11th hour due to Iran holding firm on its goal of regaining market share lost under economic sanctions.

The situation is shaping up the same this time out. "Once again, it seems (Saudi Deputy Crown Prince Mohammed bin Salman) has decided Iranian participation in a cut is mandated," said Croft, adding, "If he sticks to that position, it doesn't lift off tomorrow.

"I think a cut was never on the table for Iran."

The current disagreement is reportedly whether Iran accepts a production level 200,000 barrels below what it says it now produces: Iran claims it produces 3.9 million barrels per day (bpd), and other sources put it closer to 3.7 million bpd.

Not surprisingly, Bijan Zanganeh, oil minister for the Islamic republic told reporters as he arrived in Vienna on Monday, "We will leave the level of production (where) we decided in Algeria" – meaning, no cuts at all.

Now that almost all hope is lost for a meaningful outcome on November 30, one question remains: "Now I'm wondering how ugly it's going to get," said John Kilduff, founding partner at Again Capital, and called OPEC "a dysfunctional family; they tried to cover up their discord as long as they could."

Kilduff thinks oil will quickly drop to $40 per barrel if Wednesday's outcome plays out as expected, then fall into the $30s soon afterwards.

Croft expressed surprise that the cutback deal will likely fall apart over a dispute of 200,000 barrels: "We're in the realm of ego ... this is kind of lunacy: they're not fighting over a million barrels."

But the surprise is confusing, considering many analysts and industry experts – first and foremost Kilduff – never thought the deal would be ratified anyway given the long-standing rivalry between OPEC members; moreover, the deal was also roundly dismissed as having almost no potential to affect the all-important global oversupply, given that the Saudis, Iran, non-member Russia, and many other nations are pumping oil at record volumes.

While analysts foment in Vienna, more distant observers such as CBC News's Don Pittiswrites that "Fixing prices above what the market is demanding now will only mean that the price fixers lose market share" and that OPEC is poised to lose considerable market share in a world awash in oil – to the benefit of Canadian and U.S. producers.

According to Statista's Middle East Research and Information Project, that process is already underway: OPEC's share of global production has dropped from 54 percent in 1973 to 42 percent today.

Jamie Webster, a fellow at the Columbia Centre for Global Energy Policy told CNBC, "This is no longer a unipolar market, this is a multi-polar market."